The present invention generally relates to turbine engines and, more particularly, to a method and system for improving aircraft fuel consumption by selectively closing one or more aircraft surge bleed valves when the surge bleed valves would normally be open.
Typically, high pressure ratio gas turbine engines require a variable engine air compressor geometry to avoid engine compressor surge. This variable geometry often includes the use of one or more surge bleed valves (SBV) for surge bleed. The surge bleed valve vents air from a compressor, increasing the distance between the engine operating line and the compressor surge line. The increased distance prevents compressor surge.
The aircraft also needs engine bleed for the environment control system (ECS) and wing de-icing. At any moment, the aircraft may or may not be extracting bleed air from the engine, as this is controlled by the ECS and the pilot. Like surge bleed, aircraft engine bleed requirements improve engine surge margin. However, use of the surge bleed via SBV and/or aircraft engine bleed causes increased fuel consumption at constant thrust.
As can be seen, there is a need for a method and system for improving aircraft fuel consumption by selectively closing one or more aircraft surge bleed valves when the surge bleed valves would normally be open and the aircraft is extracting bleed air from the engine.
In one aspect of the present invention, a method for reducing aircraft engine fuel consumption by selectively closing an aircraft surge bleed valve (SBV) when the surge bleed valve would normally be open, comprises of determining whether the engine bleed flow obtained with a closed SBV is sufficient to prevent engine surge for the present flight regime; and, if so, keeping the SBV closed while the aircraft is drawing air from the engine.
In another aspect of the present invention, a system for reducing aircraft engine fuel consumption by selectively closing an aircraft surge bleed valve (SBV) when the surge bleed valve would normally be open, comprises of means for determining whether the engine bleed flow obtained with the closed SBV is sufficient to prevent engine surge for the present flight regime; and means for keeping the SBV closed, while the aircraft is drawing air from the engine.
These and other features, aspects and advantages of the present invention will become better understood with reference to the following drawings, description and claims.